The phrase walking on eggshells really relates to our dealing with unstable people and how they react impulsively in anger or distress at the slightest provocation.
We tend to feel very uncomfortable with these people because they are so unpredictable.
There is even a walking on eggshells borderline personality disorder that relates to people who suffer from intense feelings of abandonment. They often engage in behaviors that are harmful like promiscuity, excessive spending and overeating.
In addition, they also have suicidal thoughts and extremes in feelings toward people. They may hate a person one day and love them the next.
There is a book called Stop Walking on Eggshell written by Paul Mason and Randi Kreger for family members of people afflicted with this disorder.